This project adheres to [the Python form of Semantic Versioning](https://packaging.python.org/tutorials/distributing-packages/#choosing-a-versioning-scheme) (or at least we try).
Contributors to this file, please follow the guidelines on [keepachangelog.com](http://keepachangelog.com/).
Note that each version (or "release") is the name of a [Git _tag_](https://git-scm.com/book/en/v2/Git-Basics-Tagging) of a particular commit, so the associated date and time are the date and time of that commit (as reported by GitHub), _not_ the "Uploaded on" date listed on PyPI (which may differ).
For reference, the possible headings are:
* **Added** for new features.
* **Changed** for changes in existing functionality.
* **Deprecated** for once-stable features removed in upcoming releases.
* **Removed** for deprecated features removed in this release.
* **Fixed** for any bug fixes.
* **Security** to invite users to upgrade in case of vulnerabilities.
* New and improved installation setup docs and code. Pull requests [#1775](https://github.com/bigchaindb/bigchaindb/pull/1775) and [#1785](https://github.com/bigchaindb/bigchaindb/pull/1785)
* New BigchainDB configuration setting to set the port number of the log server: `log.port`. [Pull request #1796](https://github.com/bigchaindb/bigchaindb/pull/1796)
* New secondary index on `id` in the bigchain table. That will make some queries execute faster. [Pull request #1803](https://github.com/bigchaindb/bigchaindb/pull/1803)
* When using MongoDB, there are some restrictions on allowed names for keys (JSON keys). Those restrictions were always there but now BigchainDB checks key names explicitly, rather than leaving that to MongoDB. Pull requests [#1807](https://github.com/bigchaindb/bigchaindb/pull/1807) and [#1811](https://github.com/bigchaindb/bigchaindb/pull/1811)
* When using MongoDB, there are some restrictions on the allowed values of "language" (if that key is used in the values of `metadata` or `asset.data`). Those restrictions were always there but now BigchainDB checks the values explicitly, rather than leaving that to MongoDB. Pull requests [#1806](https://github.com/bigchaindb/bigchaindb/pull/1806) and [#1811](https://github.com/bigchaindb/bigchaindb/pull/1811)
* There's a new page in the root docs about permissions in BigchainDB. [Pull request #1788](https://github.com/bigchaindb/bigchaindb/pull/1788)
* There's a new option in the `bigchaindb start` command: `bigchaindb start --no-init` will avoid doing `bigchaindb init` if it wasn't done already. [Pull request #1814](https://github.com/bigchaindb/bigchaindb/pull/1814)
### Fixed
* Fixed a bug where setting the log level in a BigchainDB config file didn't have any effect. It does now. [Pull request #1797](https://github.com/bigchaindb/bigchaindb/pull/1797)
* The docs were wrong about there being no Ping/Pong support in the Events API. There is, so the docs were fixed. [Pull request #1799](https://github.com/bigchaindb/bigchaindb/pull/1799)
* Fixed an issue with closing WebSocket connections properly. [Pull request #1819](https://github.com/bigchaindb/bigchaindb/pull/1819)
### Notes
* Many changes were made to the Kubernetes-based production deployment template and code.
* Support for server-side plugins that can add support for alternate event consumers (other than the WebSocket API). [Pull request #1707](https://github.com/bigchaindb/bigchaindb/pull/1707)
* New configuration settings to set the *advertised* wsserver scheme, host and port. (The *advertised* ones are the ones that external users use to connect to the WebSocket API.) [Pull request #1703](https://github.com/bigchaindb/bigchaindb/pull/1703)
* Support for secure (TLS) WebSocket connections. [Pull request #1619](https://github.com/bigchaindb/bigchaindb/pull/1619)
* A new page of documentation about the contents of a condition (inside a transaction). [Pull request #1668](https://github.com/bigchaindb/bigchaindb/pull/1668)
### Changed
* We updated our definition of the **public API** (at the top of this document). [Pull request #1700](https://github.com/bigchaindb/bigchaindb/pull/1700)
* The HTTP API Logger now logs the request path and method as well. [Pull request #1644](https://github.com/bigchaindb/bigchaindb/pull/1644)
* Many improvements to our production deployment template (which uses Kubernetes).
* The production deployment template for the multi-node case was out of date. We updated that and verified it. [Pull request #1713](https://github.com/bigchaindb/bigchaindb/pull/1713)
**This just reports the changes since the release of 1.0.0rc1. If you want the full picture of all changes since 0.10, then read the 1.0.0rc1 change log below as well as the upgrade guide.**
### Changed
* The file name of the upgrade guide changed from `docs/upgrade-guides/v0.10-->v1.0.md` to `docs/upgrade-guides/v0.10-v1.0.md`.
* In `transaction.inputs[n].fulfills`, `output` was renamed to `output_index`. [Pull Request #1596](https://github.com/bigchaindb/bigchaindb/pull/1596)
* In `transaction.outputs[n].condition.details`, 1) `signature` was removed (from signature conditions) and 2) `subfulfillments` was renamed to `subconditions` (in threshold conditions). [Pull Request #1589](https://github.com/bigchaindb/bigchaindb/pull/1589)
* Refined transaction schema validation to check that the `transaction.outputs[n].condition.uri` corresponds to a condition that BigchainDB Server 1.0.0 actually supports. [Pull Request #1597](https://github.com/bigchaindb/bigchaindb/pull/1597)
* Before, GET requests (to the HTTP API) with header `Content-Type: 'application/json'` would get a response with the message, "The browser (or proxy) sent a request that this server could not understand." Now, if a GET request includes a `Content-Type` header, that header gets deleted (i.e. ignored). [Pull Request #1630](https://github.com/bigchaindb/bigchaindb/pull/1630)
* If an end user sends a transaction with `operation` equal to `GENESIS`, it will be rejected as invalid. [Pull Request #1612](https://github.com/bigchaindb/bigchaindb/pull/1612)
* Text search support (only if using MongoDB). Pull Requests [#1469](https://github.com/bigchaindb/bigchaindb/pull/1469) and [#1471](https://github.com/bigchaindb/bigchaindb/pull/1471)
* The `database.connection_timeout` configuration setting now works with RethinkDB too. [#1512](https://github.com/bigchaindb/bigchaindb/pull/1512)
* New code and tools for benchmarking CREATE transactions. [Pull Request #1511](https://github.com/bigchaindb/bigchaindb/pull/1511)
### Changed
* There's an upgrade guide in `docs/upgrade-guides/v0.10-->v1.0.md`. It only covers changes to the transaction model and HTTP API. If that file hasn't been merged yet, see [Pull Request #1547](https://github.com/bigchaindb/bigchaindb/pull/1547)
* Cryptographic signatures now sign the whole (serialized) transaction body, including the transaction ID, but with all `"fulfillment"` values changed to `None`. [Pull Request #1225](https://github.com/bigchaindb/bigchaindb/pull/1225)
* In transactions, the value of `"amount"` must be a string. (Before, it was supposed to be a number.) [Pull Request #1286](https://github.com/bigchaindb/bigchaindb/pull/1286)
* In `setup.py`, the "Development Status" (as reported on PyPI) was changed from Alpha to Beta. [Pull Request #1437](https://github.com/bigchaindb/bigchaindb/pull/1437)
* If you explicitly specify a config file, e.g. `bigchaindb -c path/to/config start` and that file can't be found, then BigchainDB Server will fail with a helpful error message. [Pull Request #1486](https://github.com/bigchaindb/bigchaindb/pull/1486)
* Reduced the response time on the HTTP API endpoint to get all the unspent outputs associated with a given public key (a.k.a. "fast unspents"). [Pull Request #1411](https://github.com/bigchaindb/bigchaindb/pull/1411)
* Internally, the value of an asset's `"data"` is now stored in a separate assets table. This enabled the new text search. Each asset data is stored along with the associated CREATE transaction ID (asset ID). That data gets written when the containing block gets written to the bigchain table. [Pull Request #1460](https://github.com/bigchaindb/bigchaindb/pull/1460)
* Schema validation was sped up by switching to `rapidjson-schema`. [Pull Request #1494](https://github.com/bigchaindb/bigchaindb/pull/1494)
* If a node comes back from being down for a while, it will resume voting on blocks in the order determined by the MongoDB oplog, in the case of MongoDB. (In the case of RethinkDB, blocks missed in the changefeed will not be voted on.) [Pull Request #1389](https://github.com/bigchaindb/bigchaindb/pull/1389)
* Parallelized transaction schema validation in the vote pipeline. [Pull Request #1492](https://github.com/bigchaindb/bigchaindb/pull/1492)
*`asset.data` or `asset.id` are now *required* in a CREATE or TRANSFER transaction, respectively. [Pull Request #1518](https://github.com/bigchaindb/bigchaindb/pull/1518)
* The HTTP response body, in the response to the `GET /` and the `GET /api/v1` endpoints, was changed substantially. [Pull Request #1529](https://github.com/bigchaindb/bigchaindb/pull/1529)
* Changed the HTTP `GET /api/v1/transactions/{transaction_id}` endpoint. It now only returns the transaction if it's in a valid block. It also returns a new header with a relative link to a status monitor. [Pull Request #1543](https://github.com/bigchaindb/bigchaindb/pull/1543)
* All instances of `txid` and `tx_id` were replaced with `transaction_id`, in the transaction model and the HTTP API. [Pull Request #1532](https://github.com/bigchaindb/bigchaindb/pull/1532)
* The hostname and port were removed from all URLs in all HTTP API responses. [Pull Request #1538](https://github.com/bigchaindb/bigchaindb/pull/1538)
* Relative links were replaced with JSON objects in HTTP API responses. [Pull Request #1541](https://github.com/bigchaindb/bigchaindb/pull/1541)
* In the outputs endpoint of the HTTP API, the query parameter `unspent` was changed to `spent` (so no more double negatives). If that query parameter isn't included, then all outputs matching the specificed public key will be returned. If `spent=true`, then only the spent outputs will be returned. If `spent=false`, then only the unspent outputs will be returned. [Pull Request #1545](https://github.com/bigchaindb/bigchaindb/pull/1545)
* The supported crypto-conditions changed from version 01 of the crypto-conditions spec to version 02. [Pull Request #1562](https://github.com/bigchaindb/bigchaindb/pull/1562)
* The value of "version" inside a transaction must now be "1.0". (Before, it could be "0.anything".) [Pull Request #1574](https://github.com/bigchaindb/bigchaindb/pull/1574)
* The `server.threads` configuration setting (for the Gunicorn HTTP server) was removed from the default set of BigchainDB configuration settings. [Pull Request #1488](https://github.com/bigchaindb/bigchaindb/pull/1488)
* The `GET /api/v1/outputs` endpoint was failing for some transactions with threshold conditions. Fixed in [Pull Request #1450](https://github.com/bigchaindb/bigchaindb/pull/1450)
* There were many improvements to our Kubernetes-based production deployment template (and the associated documentaiton).
* There is now a [BigchainDB Ruby driver](https://github.com/LicenseRocks/bigchaindb_ruby), created by @addywaddy at [license.rocks](https://github.com/bigchaindb/bigchaindb/pull/1437).
* The [BigchainDB JavaScript driver](https://github.com/bigchaindb/js-bigchaindb-driver) was moved to a different GitHub repo and is now officially maintained by the BigchainDB team.
* Documentation for the BigchainDB settings `wsserver.host` and `wsserver.port`. [Pull Request #1408](https://github.com/bigchaindb/bigchaindb/pull/1408)
* Fixed `Dockerfile`, which was failing to build. It now starts `FROM python:3.6` (instead of `FROM ubuntu:xenial`). [Pull Request #1410](https://github.com/bigchaindb/bigchaindb/pull/1410)
* Fixed the `Makefile` so that `release` depends on `dist`. [Pull Request #1405](https://github.com/bigchaindb/bigchaindb/pull/1405)
* The main BigchainDB Dockerfile (and its generated Docker image) now contains only BigchainDB Server. (It used to contain both BigchainDB Server and RethinkDB.) You must now run MongoDB or RethinkDB in a separate Docker container. [Pull Request #1174](https://github.com/bigchaindb/bigchaindb/pull/1174)
* Made separate schemas for CREATE and TRANSFER transactions. [Pull Request #1257](https://github.com/bigchaindb/bigchaindb/pull/1257)
* When signing transactions with threshold conditions, we now sign all subconditions for a public key. [Pull Request #1294](https://github.com/bigchaindb/bigchaindb/pull/1294)
* Many changes to the voting-related code, including how we validate votes and prevent duplicate votes by the same node. Pull Requests [#1215](https://github.com/bigchaindb/bigchaindb/pull/1215) and [#1258](https://github.com/bigchaindb/bigchaindb/pull/1258)
### Removed
* Removed the `bigchaindb load` command. Pull Requests
* Removed old `/speed-tests` and `/benchmarking-tests` directories. [Pull Request #1359](https://github.com/bigchaindb/bigchaindb/pull/1359)
### Fixed
* Fixed the URL of the BigchainDB docs returned by the HTTP API. [Pull Request #1178](https://github.com/bigchaindb/bigchaindb/pull/1178)
* Fixed the MongoDB changefeed: it wasn't reporting update operations. [Pull Request #1193](https://github.com/bigchaindb/bigchaindb/pull/1193)
* Fixed the block-creation process: it wasn't checking if the transaction was previously included in:
* a valid block. [Pull Request #1208](https://github.com/bigchaindb/bigchaindb/pull/1208)
* the block-under-construction. Pull Requests [#1237](https://github.com/bigchaindb/bigchaindb/issues/1237) and [#1377](https://github.com/bigchaindb/bigchaindb/issues/1377)
* Fixed bug in how the transaction `VERSION` string was calculated from the BigchainDB Server `__short_version__` string. [Pull Request #1160](https://github.com/bigchaindb/bigchaindb/pull/1160)
It has been more than two months since the v0.8.0 release, so there have been _many_ changes. We decided to describe them in broad strokes, with links to more details elsewhere.
### Added
- Support for MongoDB as a backend database.
- Some configuration settings and `bigchaindb` command-line commands were added. In particular, one can specify the database backend (`rethinkdb` or `mongodb`). For MongoDB, one can specify the name of the replicaset. Also for MongoDB, there are new command-line commands to add and remove hosts from the replicaset. See [the Settings & CLI docs](https://docs.bigchaindb.com/projects/server/en/v0.9.0/server-reference/index.html).
- Transaction schema validation. The transaction schema is also used to auto-generate some docs. [Pull Request #880](https://github.com/bigchaindb/bigchaindb/pull/880)
- Vote schema validation. The vote schema is also used to auto-generate some docs. [Pull Request #865](https://github.com/bigchaindb/bigchaindb/pull/865)
- New `ENABLE_WEB_ADMIN` setting in the AWS deployment configuration file. [Pull Request #1015](https://github.com/bigchaindb/bigchaindb/pull/1015)
### Changed
- The transaction model has changed substantially. @libscott wrote a blog post about the changes and it will be published soon on [the BigchainDB Blog](https://blog.bigchaindb.com/). Also, see [the docs about the transaction model](https://docs.bigchaindb.com/projects/server/en/v0.9.0/data-models/transaction-model.html).
- The HTTP API has changed substantially. @diminator wrote a blog post about the changes and it will be published soon on [the BigchainDB Blog](https://blog.bigchaindb.com/). Also, see [the docs about the vote model](https://docs.bigchaindb.com/projects/server/en/v0.9.0/data-models/vote-model.html).
- All RethinkDB-specific database calls were replaced with abstract calls to a backend database.
- Some improvements to the Dockerfile, e.g. Pull Requests [#1011](https://github.com/bigchaindb/bigchaindb/pull/1011) and [#1121](https://github.com/bigchaindb/bigchaindb/pull/1121)
- Many improvements to the tests
- We standardized on supporting Ubuntu 16.04 for now (but BigchainDB Server also works on similar Linux distros).
### Removed
-`api_endpoint` was removed from the BigchainDB configuration settings. (It was never used anyway.) [Pull Request #821](https://github.com/bigchaindb/bigchaindb/pull/821)
- Removed all remaining StatsD monitoring code, configuration settings, docs, etc. (We'll add another monitoring solution in the future.) [Pull Request #1138](https://github.com/bigchaindb/bigchaindb/pull/1138)
- Fixed a memory (RAM) overflow problem when under heavy load by bounding the size of the queue at the entrance to the block pipeline. [Pull Request #908](https://github.com/bigchaindb/bigchaindb/pull/908)
-@amirelemam - [Pull Request #762](https://github.com/bigchaindb/bigchaindb/pull/762) (closed but used as the basis for [Pull Request #1074](https://github.com/bigchaindb/bigchaindb/pull/1074))
- There were many additions and changes to the documentation. Fun fact: The JSON in the HTTP API docs is now auto-generated to be consistent with the current code.
- There's a draft spec for a BigchainDB Event Stream API and we welcome your feedback. See [Pull Request #1086](https://github.com/bigchaindb/bigchaindb/pull/1086)
- The big new thing in version 0.8.0 is support for divisible assets, i.e. assets like carrots or thumbtacks, where the initial CREATE transaction can register/create some amount (e.g. 542 carrots), the first TRANSFER transaction can split that amount across multiple owners, and so on. [Pull Request #794](https://github.com/bigchaindb/bigchaindb/pull/794)
- CREATE transactions must now be signed by all `owners_before` (rather than by a federation node). [Pull Request #794](https://github.com/bigchaindb/bigchaindb/pull/794)
- The user-provided timestamp was removed from the transaction data model (schema). [Pull Request #817](https://github.com/bigchaindb/bigchaindb/pull/817)
-`get_transaction()` will now return a transaction from the backlog, even if there are copies of the transaction in invalid blocks. [Pull Request #793](https://github.com/bigchaindb/bigchaindb/pull/793)
- Several pull requests to introduce a generalized database interface, to move RethinkDB calls into a separate implementation of that interface, and to work on a new MongoDB implementation of that interface. Pull Requests
- Updates to the configs and scripts for deploying a test network on AWS. The example config file deploys virtual machines running Ubuntu 16.04 now. Pull Requests
- Changed logging of transactions on block creation so now it just says the length of the list of transactions, rather than listing all the transactions. [Pull Request #861](https://github.com/bigchaindb/bigchaindb/pull/861)
### Fixed
- Equality checks with AssetLinks. [Pull Request #825](https://github.com/bigchaindb/bigchaindb/pull/825)
- Bug in `bigchaindb load`. [Pull Request #824](https://github.com/bigchaindb/bigchaindb/pull/824)
- Bug in AWS deployment scripts. Setting `BIND_HTTP_TO_LOCALHOST` to `False` didn't actually work. It does now. [Pull Request #870](https://github.com/bigchaindb/bigchaindb/pull/870)
-@ChristianGaertner added a Python style checker (Flake8) to Travis CI, so external contributors should be aware that the Python code in their pull requests will be checked. See [our Python Style Guide](PYTHON_STYLE_GUIDE.md).
- Several additions and changes to the documentation, e.g. Pull Requests
- Stale transactions in the `backlog` table now get reassigned to another node (for inclusion in a new block): [Pull Request #359](https://github.com/bigchaindb/bigchaindb/pull/359)
- Many improvements to make the database connection more robust: [Pull Request #623](https://github.com/bigchaindb/bigchaindb/pull/623)
- The new `--dev-allow-temp-keypair` option on `bigchaindb start` will generate a temporary keypair if no keypair is found. The `Dockerfile` was updated to use this. [Pull Request #635](https://github.com/bigchaindb/bigchaindb/pull/635)
- The AWS deployment scripts now allow you to:
- specify the AWS security group as a configuration parameter: [Pull Request #620](https://github.com/bigchaindb/bigchaindb/pull/620)
- tell RethinkDB to bind HTTP to localhost (a more secure setup; now the default in the example config file): [Pull Request #666](https://github.com/bigchaindb/bigchaindb/pull/666)
### Changed
- Integrated the new `Transaction` model. This was a **big** change; 49 files changed. [Pull Request #641](https://github.com/bigchaindb/bigchaindb/pull/641)
- Merged "common" code (used by BigchainDB Server and the Python driver), which used to be in its own repository (`bigchaindb/bigchaindb-common`), into the main `bigchaindb/bigchaindb` repository (this one): [Pull Request #742](https://github.com/bigchaindb/bigchaindb/pull/742)
- Integrated the new digital asset model. This changed the data structure of a transaction and will make it easier to support divisible assets in the future. [Pull Request #680](https://github.com/bigchaindb/bigchaindb/pull/680)
- Transactions are now deleted from the `backlog` table _after_ a block containing them is written to the `bigchain` table: [Pull Request #609](https://github.com/bigchaindb/bigchaindb/pull/609)
- Changed the example AWS deployment configuration file: [Pull Request #665](https://github.com/bigchaindb/bigchaindb/pull/665)
- Support for version 0.5.0 of the `cryptoconditions` Python package. Note that this means you must now install `ffi.h` (e.g. `sudo apt-get install libffi-dev` on Ubuntu). See Pull Requests [#685](https://github.com/bigchaindb/bigchaindb/pull/685) and [#698](https://github.com/bigchaindb/bigchaindb/pull/698)
- Updated some database access code: Pull Requests [#676](https://github.com/bigchaindb/bigchaindb/pull/676) and [#701](https://github.com/bigchaindb/bigchaindb/pull/701)
### Fixed
- Internally, when a transaction is in the `backlog` table, it carries some extra book-keeping fields:
1. an `assignment_timestamp` (i.e. the time when it was assigned to a node), which is used to determine if it has gone stale.
2. an `assignee`: the public key of the node it was assigned to.
- The `assignment_timestamp` wasn't removed before writing the transaction to a block. That was fixed in [Pull Request #627](https://github.com/bigchaindb/bigchaindb/pull/627)
- The `assignment_timestamp` and `assignee` weren't removed in the response to an HTTP API request sent to the `/api/v1/transactions/<txid>` endpoint. That was fixed in [Pull Request #646](https://github.com/bigchaindb/bigchaindb/pull/646)
- When validating a TRANSFER transaction, if any fulfillment refers to a transaction that's _not_ in a valid block, then the transaction isn't valid. This wasn't checked before but it is now. [Pull Request #629](https://github.com/bigchaindb/bigchaindb/pull/629)
- We made a small change to how we do version labeling. Going forward, we will have the version label set to 0.X.Y.dev in the master branch as we work on what will eventually be released as version 0.X.Y. The version number will only be changed to 0.X.Y just before the release. This version labeling scheme began with [Pull Request #752](https://github.com/bigchaindb/bigchaindb/pull/752)
- Check that the majority of votes on a block agree on the previous block. If they don't, consider the block invalid. [Pull Request #565](https://github.com/bigchaindb/bigchaindb/pull/565)
### Changed
- Set RethinkDB `read-mode='majority'` everywhere: [Pull Request #497](https://github.com/bigchaindb/bigchaindb/pull/497)
- Ported election logic and voting logic to the new pipeline architecture: Pull Requests [#510](https://github.com/bigchaindb/bigchaindb/pull/510) and [#515](https://github.com/bigchaindb/bigchaindb/pull/515)
- Moved the transaction (model) `version` inside the `transaction` (in the transaction data model): [Pull Request #518](https://github.com/bigchaindb/bigchaindb/pull/518)
- Changed how the BigchainDB config file (JSON) gets written so it's easier for humans to read: [Pull Request #522](https://github.com/bigchaindb/bigchaindb/pull/522)
- Improved and expanded the GET/POST endpoints for transactions (in the HTTP API): [Pull Request #563](https://github.com/bigchaindb/bigchaindb/pull/563)
- Changed the AWS cluster deployment scripts so that the deployer now generates their keypair locally, rather than having Amazon do it: [Pull Request #567](https://github.com/bigchaindb/bigchaindb/pull/567)
- When a transaction is retrieved by `get_transaction`, a `validity` field is added with a value one of `valid`, `undecided`, or `backlog`: [Pull Request #574](https://github.com/bigchaindb/bigchaindb/pull/574)
- Renamed `current_owners` and `new_owners` (in the data models) to `owners_before` and `owners_after`, respectively (i.e. before/after *the transaction*): [Pull Request #578](https://github.com/bigchaindb/bigchaindb/pull/578)
- Use `flask_restful` and class-based views for realizing the HTTP API: [Pull Request #588](https://github.com/bigchaindb/bigchaindb/pull/588)
### Fixed
- Fixed the confusing error message when there was a syntax error in the BigchainDB config file: [Pull Request #531](https://github.com/bigchaindb/bigchaindb/pull/531)
- Fixed `write_transaction` so it no longer has the side effect of adding `assignee` to a transaction that is being processed: [Pull Request #606](https://github.com/bigchaindb/bigchaindb/pull/606)
- New third table, the 'votes' table: [Pull Request #379](https://github.com/bigchaindb/bigchaindb/pull/379)
- Added `get_tx_by_payload_uuid()` including index: [Pull Request #411](https://github.com/bigchaindb/bigchaindb/pull/411)
- Ability to deploy a test cluster on AWS using Amazon Elastic Block Store (EBS) for storage: [Pull Request #469](https://github.com/bigchaindb/bigchaindb/pull/469)
- Ability to add different-size payloads to transactions when filling the backlog for benchmarking: [Pull Request #273](https://github.com/bigchaindb/bigchaindb/pull/273)
### Changed
- Votes are no longer appended to the blocks inside the 'bigchain' table. They're now written to their own table, the 'votes' table: [Pull Request #379](https://github.com/bigchaindb/bigchaindb/pull/379)
- Refactored how blocks get constructed using the new approach to doing multiprocessing, using the `multipipes` package: [Pull Request #484](https://github.com/bigchaindb/bigchaindb/pull/484)
- Changed all queries to use `read_mode='majority'`: [Pull Request #497](https://github.com/bigchaindb/bigchaindb/pull/497)
- Revised how base software gets deployed on AWS instances: [Pull Request #478](https://github.com/bigchaindb/bigchaindb/pull/478)
- New `bigchaindb set-replicas` subcommand: [Pull Request #392](https://github.com/bigchaindb/bigchaindb/pull/392)
- Informative JSON message when one makes a request to the root endpoint of the HTTP client-server API: [Pull Request #367](https://github.com/bigchaindb/bigchaindb/pull/367)
- Return HTTP response code 404 when a transaction is not found: [Pull Request #369](https://github.com/bigchaindb/bigchaindb/pull/369)
### Changed
- Changed the order in which configuration settings get their values. If a setting is set by an environment variable, then that value will be _the_ value, regardless of whether another value is set in a local config file. Also added a method to programattically update the config settings. [Pull Request #395](https://github.com/bigchaindb/bigchaindb/pull/395)
- Changed the definition of `util.sign_tx()`. It now has a third, optional argument: a Bigchain instance. [Pull Request #410](https://github.com/bigchaindb/bigchaindb/pull/410)
- Report the BigchainDB version number when starting BigchainDB: [Pull Request #385](https://github.com/bigchaindb/bigchaindb/pull/385)
### Changed
- Round timestamps to a precision of one second, and replace payload hash with payload UUID in transactions: [Pull Request #384](https://github.com/bigchaindb/bigchaindb/pull/384)
- Support for escrow (possible because of two other new things: cryptoconditions with inverters, and a timeout condition): [Pull Request #329](https://github.com/bigchaindb/bigchaindb/pull/329)
- Caching of calls to `load_consensus_plugin()`, using [`@lru_cache`](https://docs.python.org/3/library/functools.html#functools.lru_cache). This speeds up the instantiation of `Bigchain` objects and greatly improves overall performance. [Pull Request #271](https://github.com/bigchaindb/bigchaindb/pull/271)
- New `Dockerfile-dev` Docker file to make it easier for developers to _develop_ BigchainDB with Docker. One can run all unit tests with Docker again. [Pull Request #313](https://github.com/bigchaindb/bigchaindb/pull/313)
- Transactions in invalid blocks are copied to the backlog: [Pull Request #221](https://github.com/bigchaindb/bigchaindb/pull/221).
- New `bigchaindb` command to set the number of RethinkDB shards (in both tables): [Pull Request #258](https://github.com/bigchaindb/bigchaindb/pull/258)
- The block processes now use GroupProcess: [Pull Request #267](https://github.com/bigchaindb/bigchaindb/pull/267)
- Replaced the `json` Python package with `rapidjson` (a Python wrapper for a fast JSON parser/generator written in C++), to speed up JSON serialization and deserialization: [Pull Request #318](https://github.com/bigchaindb/bigchaindb/pull/318)
- AWS deployment has better support for [New Relic Server Monitoring](https://newrelic.com/server-monitoring): [Pull Request #316](https://github.com/bigchaindb/bigchaindb/pull/316)
- AWS deployment script now reads from a configuration file: [Pull Request #291](https://github.com/bigchaindb/bigchaindb/pull/291)
- Ability to use environment variables to set (or partially set) configuration settings: [Pull Request #153](https://github.com/bigchaindb/bigchaindb/pull/153)
-`bigchaindb --version`, and one central source for the current version (`version.py`): [Pull Request #208](https://github.com/bigchaindb/bigchaindb/pull/208)
- Rewrote [`README.md`](README.md) into four sets of links: Pull Requests [#80](https://github.com/bigchaindb/bigchaindb/pull/80) and [#115](https://github.com/bigchaindb/bigchaindb/pull/115)
- [Issue #71](https://github.com/bigchaindb/bigchaindb/issues/71) (Voter is not validating blocks correctly when checking for double spends) in [Pull Request #76](https://github.com/bigchaindb/bigchaindb/pull/76)
-`requirements.txt` in the root directory, and the entire `requirements/` directory: [Pull Request #14](https://github.com/bigchaindb/bigchaindb/pull/14)